Early color IF trap settings
We should not mess with these I know, but if there was someone who did before, what is your best method?
Im working on RCA's CTC 11, 12 and 16 chassis now and there is excessive noise in the video that the fine-tuning can seem to get rid of. This is not ringing or smeary stuff but possible too much high-frequency video response And where is the 3.58 mc trap located, as it is merely mentioned in Sencore's VA-48 manual -assuming it varies between models? |
If the traps are off, the main alignment probably is too.
In contradiction to what is usually said here, ALL of my postwar sets have been off in alignment, so a modest amount, some horribly. There is no cure except good equipment and following instructions. If you have the rare set where you can't find instructions, you need to carefully note settings. I count turns on variable caps and measure slug positions with a vernier caliper. Then carefully tweek. If you don't have experience, even with instructions, measure first so you can reset if it gets out of hand (like oscillation). Interestingly, if my TRK-12 had been a color set ... no alignment would have been necessary ... it was a textbook-perfect image of the CT-100 response as I got it. Of course, this had been a research-lab test chassis. My avatar was only achieved after doing a really careful alignment job. "Before" you could have seen the problems in that icon-sized image! Of course traps are easier, since they can be set to an exact frequency. |
BK 415 sweep gen.
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Think Ill hook up a scope to the video detector next, run the Sencore in at the tuner-IF link and compare it to the book. Later Ill try the RCA WR-69 Sweep Generator - of course then clamping the AGC is needed or it will reduce IF gain to minimum. Sometimes it helps to use the same vintage test equipment, assuming its functioning properly. |
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